My dad, who is an engineer by schooling (software engineer by profession) figured out how to add a counterweight onto the end of my scale to add 100lbs to its balance, thus increasing the amount of weight it can measure up to 450lbs.
I'm almost down below 350lbs now (the upper end of the scale) so in a month or two I'll not need it anyway, but it's really amazingly accurate. It's a pretty decent doctor's scale that my dad bought years ago at a medical supply place. It's much nicer and sturdier than the scale that my actual doctor has in her office.
Anyway, I've been reading The Hacker's Diet and I think his suggestions for how to measure water balance and BMI are very good. I may even weigh myself once in the morning and then once again before I go to bed just to collect the data (although again, for my goal-setting I am only counting Tuesday morning's weigh-in as my +/- weight for each week).
My new Get.FitWith.Us software will let people add weight check-in points any time they want, and will graph ups and downs, coming up with an average gain/loss number that will be a fairly accurate measure of actual weight, and then suggest caloric intake and possible exercise routines to maintain consistent and reasonable weight loss.
This stuff isn't rocket science, but it is science, and applying logic and math to my fitness rather than the emotional component I used to assign it (not that I can get away from my emotions, of course, but the science helps me not feel too badly about my body) I'm noticing real, calculable results, which in turn generate good feelings of self-worth and positive feelings that I can get my body into shape.
Coming up: weight training, and all of the fun maths involved in trying to calculate both muscle mass gain and weight loss of fat and such. I have no idea yet how to account for muscle building when dealing with weight loss, but by this time next month I'll be an expert.
More to come.